It seems like we are not lacking in new discoveries beyond our planet Earth these days as astronomers revealed they have now seen a humongous disk galaxy that is unique by itself.
The newly discovered galaxy formed almost 12.5 billion years ago back when our own universe was only 13.8 billion years old. A finding such as this could open up opportunities toward astronomers on studying how galaxies really form during the early start of a universe.
When it was first spotted, the galaxy was called as the Galaxy DLA0817g, but then it got its nickname ‘Wolfe Disk’ from late astronomer, Mr. Arthur M. Wolfe. He was also a former doctoral advisor to three out of the four researchers.
The Wolfe Disk Galaxy is also the most distant rotating disk galaxy that has ever been observed thus far. We have Atacama Large Millimeter/submillimeter Array of Telescopes (ALMA in Chile) to thank for that.
Observations point out that this galaxy’s disk has a mass around 70 billion times the sun’s own measure, and is said to be rotating at a speed of 170 miles per second. This is actually a similar rotation that of our Milky Way.
However, galaxies with stable and well-formed disks (that of the Milky Way) experienced a gradual formation, popping up on the timeline of the universe with some even dated 6 billion years after Big Bang happened.
To recap what we know about this event in space: the universe was basically a blank canvas after the Big Bang’s occurrence. Then galaxies started forming with smaller galaxies merging and clashing against one another along with gas clumps. Marcel Neeleman, the lead author and postdoctoral researcher at Max Planck Institute for Astronomy located in Heidelberg, Germany, even compared the formation of galaxies to a train wreck because of their consisted and often ‘violent’ merging.
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The Wolfe Disk Galaxy came to be in a unique way known as cold-mode accretion, researchers concluded. Most galaxies, as far as astronomers knew, follows some sort of hierarchy where halo-like structures of dark matter draw in gas. Once these two components merge, star formation follows, and where stars cluster, a galaxy is born.
In the Wolfe Disk’s case, cooler gas is eluded to a new galaxy which permits a faster formation of a disk. J. Xavier Prochaska, the study’s coauthor and professor of astrophysics and astronomy at the University of California in Sta. Cruz, shared their thoughts that the Disk grew through the stead accretion of cold gas. Still, their question remains on how it was able to assemble a massive gas mass while at the same time maintain a relatively stable and rotating disk.
To further study the stars forming within the said galaxy, the researchers took to the Hubble Space Telescope data, as well as the National Science Foundation’s Karl G. Jansky Very Large Array of radio antennae found in New Mexico. It was found that formation rate of the stars in the Wolfe Disk is a minimum 10x higher than that of the Milky Way.
The galaxy was actually first spotted back in 2017 through ALMA when light from a quasar—which appears to be just a star through telescope view—passed through hydrogen gas around the galaxy for it to be spotted. Galaxies are difficult to spot, really, but because of this light method using quasars—which happens rarely—made it possible.
Neeleman commented that it is possible there are many other galaxies sharing the Wolfe Disk’s traits out there. It was also with the help of ALMA that Neeleman and his fellow researchers now have evidences that such galaxy formation occurred 1.5 billion years after the Big Bang.
In the future, astronomers could perhaps better understand that cold method of galaxy formation was a common event even back then in the early universe.